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  • Project Euler #18 - how to brute force all possible paths in tree-like structure using Python?

    - by euler user
    Am trying to learn Python the Atlantic way and am stuck on Project Euler #18. All of the stuff I can find on the web (and there's a LOT more googling that happened beyond that) is some variation on 'well you COULD brute force it, but here's a more elegant solution'... I get it, I totally do. There are really neat solutions out there, and I look forward to the day where the phrase 'acyclic graph' conjures up something more than a hazy, 1 megapixel resolution in my head. But I need to walk before I run here, see the state, and toy around with the brute force answer. So, question: how do I generate (enumerate?) all valid paths for the triangle in Project Euler #18 and store them in an appropriate python data structure? (A list of lists is my initial inclination?). I don't want the answer - I want to know how to brute force all the paths and store them into a data structure. Here's what I've got. I'm definitely looping over the data set wrong. The desired behavior would be to go 'depth first(?)' rather than just looping over each row ineffectually.. I read ch. 3 of Norvig's book but couldn't translate the psuedo-code. Tried reading over the AIMA python library for ch. 3 but it makes too many leaps. triangle = [ [75], [95, 64], [17, 47, 82], [18, 35, 87, 10], [20, 4, 82, 47, 65], [19, 1, 23, 75, 3, 34], [88, 2, 77, 73, 7, 63, 67], [99, 65, 4, 28, 6, 16, 70, 92], [41, 41, 26, 56, 83, 40, 80, 70, 33], [41, 48, 72, 33, 47, 32, 37, 16, 94, 29], [53, 71, 44, 65, 25, 43, 91, 52, 97, 51, 14], [70, 11, 33, 28, 77, 73, 17, 78, 39, 68, 17, 57], [91, 71, 52, 38, 17, 14, 91, 43, 58, 50, 27, 29, 48], [63, 66, 4, 68, 89, 53, 67, 30, 73, 16, 69, 87, 40, 31], [04, 62, 98, 27, 23, 9, 70, 98, 73, 93, 38, 53, 60, 4, 23], ] def expand_node(r, c): return [[r+1,c+0],[r+1,c+1]] all_paths = [] my_path = [] for i in xrange(0, len(triangle)): for j in xrange(0, len(triangle[i])): print 'row ', i, ' and col ', j, ' value is ', triangle[i][j] ??my_path = somehow chain these together??? if my_path not in all_paths all_paths.append(my_path) Answers that avoid external libraries (like itertools) preferred.

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  • In an AVL tree, at what condition the balancing is to be done? proper code in c languge

    - by bachchan
    Binary search follows Divide and Conquer method where as linear Search doesn't follw.The time complexity of Binary Search in O(log n) but incase of linear search the time complexity is O(n). Thats way Binary search is having bettr prior than linear search. But it is true when the list of items is large incase of smaller list linear is best(i.e.- it is only when the Best Case concern)

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  • How do I move my git repo down level in the directory tree?

    - by edude05
    I'm currently writing an app in C# using using Visual Studio. As such, VS2010 created a Solution directory with my project directories inside. So my Hierarchy is like this: Solution .git project1 project2 What I'd like to do is make it like this: Solution Project 1 .git Project 2 As of right now the files in the solution are tracked, except for the project 2 (so stuff like project.sln for example). Is there a way I can do this without rewriting the history? Thanks in advance.

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  • How to reflect over T to build an expression tree for a query?

    - by Alex
    Hi all, I'm trying to build a generic class to work with entities from EF. This class talks to repositories, but it's this class that creates the expressions sent to the repositories. Anyway, I'm just trying to implement one virtual method that will act as a base for common querying. Specifically, it will accept a an int and it only needs to perform a query over the primary key of the entity in question. I've been screwing around with it and I've built a reflection which may or may not work. I say that because I get a NotSupportedException with a message of LINQ to Entities does not recognize the method 'System.Object GetValue(System.Object, System.Object[])' method, and this method cannot be translated into a store expression. So then I tried another approach and it produced the same exception but with the error of The LINQ expression node type 'ArrayIndex' is not supported in LINQ to Entities. I know it's because EF will not parse the expression the way L2S will. Anyway, I'm hopping someone with a bit more experience can point me into the right direction on this. I'm posting the entire class with both attempts I've made. public class Provider<T> where T : class { protected readonly Repository<T> Repository = null; private readonly string TEntityName = typeof(T).Name; [Inject] public Provider( Repository<T> Repository) { this.Repository = Repository; } public virtual void Add( T TEntity) { this.Repository.Insert(TEntity); } public virtual T Get( int PrimaryKey) { // The LINQ expression node type 'ArrayIndex' is not supported in // LINQ to Entities. return this.Repository.Select( t => (((int)(t as EntityObject).EntityKey.EntityKeyValues[0].Value) == PrimaryKey)).Single(); // LINQ to Entities does not recognize the method // 'System.Object GetValue(System.Object, System.Object[])' method, // and this method cannot be translated into a store expression. return this.Repository.Select( t => (((int)t.GetType().GetProperties().Single( p => (p.Name == (this.TEntityName + "Id"))).GetValue(t, null)) == PrimaryKey)).Single(); } public virtual IList<T> GetAll() { return this.Repository.Select().ToList(); } protected virtual void Save() { this.Repository.Update(); } }

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  • Is my class structure good enough?

    - by Rivten
    So I wanted to try out this challenge on reddit which is mostly about how you structure your data the best you can. I decided to challenge my C++ skills. Here's how I planned this. First, there's the Game class. It deals with time and is the only class main has access to. A game has a Forest. For now, this class does not have a lot of things, only a size and a Factory. Will be put in better use when it will come to SDL-stuff I guess A Factory is the thing that deals with the Game Objects (a.k.a. Trees, Lumberjack and Bears). It has a vector of all GameObjects and a queue of Events which will be managed at the end of one month. A GameObject is an abstract class which can be updated and which can notify the Event Listener The EventListener is a class which handles all the Events of a simulation. It can recieve events from a Game Object and notify the Factory if needed, the latter will manage correctly the event. So, the Tree, Lumberjack and Bear classes all inherits from GameObject. And Sapling and Elder Tree inherits from Tree. Finally, an Event is defined by an event_type enumeration (LUMBERJACK_MAWED, SAPPLING_EVOLUTION, ...) and an event_protagonists union (a GameObject or a pair of GameObject (who killed who ?)). I was quite happy at first with this because it seems quite logic and flexible. But I ended up questionning this structure. Here's why : I dislike the fact that a GameObject need to know about the Factory. Indeed, when a Bear moves somewhere, it needs to know if there's a Lumberjack ! Or it is the Factory which handles places and objects. It would be great if a GameObject could only interact with the EventListener... or maybe it's not that much of a big deal. Wouldn't it be better if I separate the Factory in three vectors ? One for each kind of GameObject. The idea would be to optimize research. If I'm looking do delete a dead lumberjack, I would only have to look in one shorter vector rather than a very long vector. Another problem arises when I want to know if there is any particular object in a given case because I have to look for all the gameObjects and see if they are at the given case. I would tend to think that the other idea would be to use a matrix but then the issue would be that I would have empty cases (and therefore unused space). I don't really know if Sapling and Elder Tree should inherit from Tree. Indeed, a Sapling is a Tree but what about its evolution ? Should I just delete the sapling and say to the factory to create a new Tree at the exact same place ? It doesn't seem natural to me to do so. How could I improve this ? Is the design of an Event quite good ? I've never used unions before in C++ but I didn't have any other ideas about what to use. Well, I hope I have been clear enough. Thank you for taking the time to help me !

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  • Best tree/heap data structure for fixed set of nodes with changing values + need top 20 values?

    - by user350139
    I'm writing something like a game in C++ where I have a database table containing the current score for each user. I want to read that table into memory at the start of the game, quickly change each user's score while the game is being played in response to what each user does, and then when the game ends write the current scores back to the database. I also want to be able to find the 20 or so users with the highest scores. No users will be added or deleted during the short period when the game is being played. I haven't tried it yet, but updating the database might take too much time during the period when the game is being played. Fixed set of users (might be 10,000 to 50,000 users) Will map user IDs to their score and other user-specific information. User IDs will be auto_increment values. If the structure has a high memory overhead that's probably not an issue. If the program crashes during gameplay it can just be re-started. Quickly get a user's current score. Quickly add to a user's current score (and return their current score) Quickly get 20 users with highest score. No deletes. No inserts except when the structure is first created, and how long that takes isn't critical. Getting the top 20 users will only happen every five or ten seconds, but getting/adding will happen much more frequently. If not for the last, I could just create a memory block equal to sizeof(user) * max(user id) and put each user at user id * sizeof(user) for fast access. Should I do that plus some other structure for the Top 20 feature, or is there one structure that will handle all of this together?

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  • How to get a random node from a tree?

    - by ooboo
    It looks easy, but I found the implementation tricky. I need that for a simple genetic programming problem I'm trying to implement. The function should, given a node, return the node itself or any of its children such that the probability of choosing a node is normally distributed relative to its depth (so the function should return mostly middle nodes, but sometimes the root itself or the lowest ones - but that's not really necessary if that makes it significantly more complex, if all any node is chosen with equal probability, that's good enough). Thanks

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  • Rolling back a git tree, fully or partially (single file) how to?

    - by Tzury Bar Yochay
    On a given server, I have a set of daemons each of which has its own configuration file. I would like to use git to manage the configuration files editing during time and always have the option to rollback to the "factory defaults" in regards to all files or a specific one. For instance, given the following structure: $ ls -l total 0 -rw-r--r-- 1 tzury tzury 0 2011-01-05 06:36 bar.conf -rw-r--r-- 1 tzury tzury 0 2011-01-05 06:36 baz.conf -rw-r--r-- 1 tzury tzury 0 2011-01-05 06:36 foo.conf Assuming all those .conf files are stored in a git repository, I want to be able to restore all files into their original shape (that would be the first git commit). Yet, I would also like to be able to rollback a specific file to the factory defaults, while others remain up to date.

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  • Getting velocity in only one plane (X) in Kismet (UDK)

    - by anna1987
    I'm trying to make a character in 2.5 platformer (in UDK) to "climb" a giant tree trunk by walking on a spiral staircase enveloped around the tree. When character goes right the tree rotates thru matinee sequence so it seems that the character is moving while in reality it is the tree that moves. I connected the matinee sequence playrate to the velocity of the character and its all good as long the character just moves left or right. When it jumps though, the velocity still affects the playrate - it should not as character moves up/down, not right/left. How do I set it up in Kismet so I get a float variable with velocity only in the X plane (horizontal)?

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  • How to build a Drag and Dropable Tree using Jquery for Menu?

    - by Anil
    Hi all i want to build a Menu Builder with drag and drop which i am trying to do like here is the jsfiddle of what i am trying to do This and i want the functionality to be like This i will have all products list on a side and i should have a Add column button ,when i click on Add Column button a div should open where i should be able to drag and drop my products like the above the first product i drop in a div should be main then i should be able to add child to that particular product i should be able to add any number of submenus to it like this div1 Mens shoes SportShoes CasualShoe Shirts Casualshirts div2 Womens shoes SportShoes CasualShoe Shirts Casualshirts this is what i have to do can any one help me doing this please

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  • asp.net + How to create custom multi-templated tree databound control?

    - by ParagM
    I dont want to use asp.net's TreeView control. I want to create a custom template databound control with multi template support like - <asp:MtNavigationControl> <ItemTemplate> ... ... </ItemTemplate> <SelectedItemTemplate> ... ... </SelectedItemTemplate> <ParentItemTemplate> ... ... </ParentSelectedItemTemplate> <SelectedParentItemTemplate> ... ... </SelectedParentSelectedItemTemplate> </asp:MtNavigationControl> My data is like - class Employee { string EmployeeName List<Employee> Employees } Does anyone know how to accomplish it? Please help !!!

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  • LaTeX limitation?

    - by Jayen
    Hi, I've hit an annoying problem in LaTeX. I've got a tex file of about 1000 lines. I've already got a few figures, but when I try to add another figure, It barfs with: ! Undefined control sequence. <argument> ... \sf@size \z@ \selectfont \@currbox l.937 \begin{figure}[t] If I move the figure to other parts of the file, I can get similar errors on different lines: ! Undefined control sequence. <argument> ... \sf@size \z@ \selectfont \@currbox l.657 \paragraph {A Centering Algorithm} If I comment out the figure, all is ok. %\begin{figure}[t] % \caption{Example decision tree, from Reiter and Dale [2000]} % \label{fig:relation-decision-tree} % \centering % \includegraphics[keepaspectratio=true]{./relation-decision-tree.eps} %\end{figure} If I keep just the begin and end like: \begin{figure}%[t] % \caption{Example decision tree, from Reiter and Dale [2000]} % \label{fig:relation-decision-tree} % \centering % \includegraphics[keepaspectratio=true]{./relation-decision-tree.eps} \end{figure} I get: ! Undefined control sequence. <argument> ... \sf@size \z@ \selectfont \@currbox l.942 \end {figure} At first, I thought maybe LaTeX has hit some limit, and I tried playing with the ulimits, but that didn't help. Any ideas? i've got other figures with graphics already. my preamble looks like: \documentclass[acmcsur,acmnow]{acmtrans2n} \usepackage{array} \usepackage{lastpage} \usepackage{pict2e} \usepackage{amsmath} \usepackage{varioref} \usepackage{epsfig} \usepackage{graphics} \usepackage{qtree} \usepackage{rotating} \usepackage{tree-dvips} \usepackage{mdwlist} \makecompactlist{quote*}{quote} \usepackage{verbatim} \usepackage{ulem}

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  • JTree events seem misordered

    - by MeBigFatGuy
    It appears to me that tree selection events should happen after focus events, but this doesn't seem to be the case. Assume you have a JTree and a JTextField, where the JTextField is populated by what is selected in the tree. When the user changes the text field, on focus lost, you update the tree from the text field. however, the tree selection is changed before the focus is lost on the text field. this is incorrect, right? Any ideas? Here is some sample code: import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.event.*; public class Focus extends JFrame { public static void main(String[] args) { Focus f = new Focus(); f.setLocationRelativeTo(null); f.setVisible(true); } public Focus() { Container cp = getContentPane(); cp.setLayout(new BorderLayout()); final JTextArea ta = new JTextArea(5, 10); cp.add(new JScrollPane(ta), BorderLayout.SOUTH); JSplitPane sp = new JSplitPane(); cp.add(sp, BorderLayout.CENTER); JTree t = new JTree(); t.addTreeSelectionListener(new TreeSelectionListener() { public void valueChanged(TreeSelectionEvent tse) { ta.append("Tree Selection changed\n"); } }); t.addFocusListener(new FocusListener() { public void focusGained(FocusEvent fe) { ta.append("Tree focus gained\n"); } public void focusLost(FocusEvent fe) { ta.append("Tree focus lost\n"); } }); sp.setLeftComponent(new JScrollPane(t)); JTextField f = new JTextField(10); sp.setRightComponent(f); pack(); f.addFocusListener(new FocusListener() { public void focusGained(FocusEvent fe) { ta.append("Text field focus gained\n"); } public void focusLost(FocusEvent fe) { ta.append("Text field focus lost\n"); } }); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } }

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  • DIY intellisense on XPath - design approach? (WinForms app)

    - by Cheeso
    I read the DIY Intellisense article on code project, which was referenced from the Mimic Intellisense? question here on SO. I wanna do something similar, DIY intellisense, but for XPath not C#. The design approach used there makes sense to me: maintain a tree of terms, and when the "completion character" is pressed, in the case of C#, a dot, pop up the list of possible completions in a textfield. Then allow the user to select a term from the textfield either through typing, arrow keys, or double-click. How would you apply this to XPath autocompletion? should there be an autocomplete key? In XPath there is no obvious separator key like "dot" in C#. should the popup be triggered explicitly in some other way, let's say ctrl-. ? or should the parser try to autocomplete continuously? If I do the autocomplete continuously, how to scale it properly? There are 93 xpath functions, not counting overloads. I certainly don't want to popup a list of 93 choices. How do I decide when I've narrowed it enough to offer a useful lsit of possible completions? How to populate the tree of possible completions? For C#, it's easy: walk the type space via reflection. At a first level, the "syntax tree" for C# seems like a single tree, and the list of completions at any point depends on the graph of nodes you've traversed to that point. Typing System.Console. traverses to a certain node in that tree, and the list of completions is the set of child nodes available at that node in the tree. On the other hand, the xpath syntax seems like it is a "flatter" tree - function names, axis names, literals. Does this make sense? what have I not considered?

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  • PHP: Recursively get children of parent

    - by Nic Hubbard
    I have a function which gets the ids of all children of a parent from my DB. So, if I looked up id 7, it might return an array with 5, 6 and 10. What I then want to do, is recursively find the children of those returned ids, and so on, to the final depth of the children. I have tried to write a function to do this, but I am getting confused about recursion. function getChildren($parent_id) { $tree = Array(); $tree_string; if (!empty($parent_id)) { // getOneLevel() returns a one-dimentional array of child ids $tree = $this->getOneLevel($parent_id); foreach ($tree as $key => $val) { $ids = $this->getChildren($val); array_push($tree, $ids); //$tree[] = $this->getChildren($val); $tree_string .= implode(',', $tree); } return $tree_string; } else { return $tree; } }//end getChildren() After the function is run, I would like it to return a one-dimentional array of all the child ids that were found.

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  • Swing: what to do when a JTree update takes too long and freezes other GUI elements?

    - by java.is.for.desktop
    Hello, everyone! I know that GUI code in Java Swing must be put inside SwingUtilities.invokeAndWait or SwingUtilities.invokeLater. This way threading works fine. Sadly, in my situation, the GUI update it that thing which takes much longer than background thread(s). More specific: I update a JTree with about just 400 entries, nesting depth is maximum 4, so should be nothing scary, right? But it takes sometimes one second! I need to ensure that the user is able to type in a JTextPane without delays. Well, guess what, the slow JTree updates do cause delays for JTextPane during input. It refreshes only as soon as the tree gets updated. I am using Netbeans and know empirically that a Java app can update lots of information without freezing the rest of the UI. How can it be done? NOTE 1: All those DefaultMutableTreeNodes are prepared outside the invokeAndWait. NOTE 2: When I replace invokeAndWait with invokeLater the tree doesn't get updated. NOTE 3: Fond out that recursive tree expansion takes far the most time. NOTE 4: I'm using custom tree cell renderer, will try without and report. NOTE 4a: My tree cell renderer uses a map to cache and reuse created JTextComponents, depending on tree node (as a key). CLUE 1: Wow! Without setting custom cell renderer it's 10 times faster. I think, I'll need few good tutorials on writing custom tree cell renderers.

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  • Monads and custom traversal functions in Haskell

    - by Bill
    Given the following simple BST definition: data Tree x = Empty | Leaf x | Node x (Tree x) (Tree x) deriving (Show, Eq) inOrder :: Tree x -> [x] inOrder Empty = [] inOrder (Leaf x) = [x] inOrder (Node root left right) = inOrder left ++ [root] ++ inOrder right I'd like to write an in-order function that can have side effects. I achieved that with: inOrderM :: (Show x, Monad m) => (x -> m a) -> Tree x -> m () inOrderM f (Empty) = return () inOrderM f (Leaf y) = f y >> return () inOrderM f (Node root left right) = inOrderM f left >> f root >> inOrderM f right -- print tree in order to stdout inOrderM print tree This works fine, but it seems repetitive - the same logic is already present in inOrder and my experience with Haskell leads me to believe that I'm probably doing something wrong if I'm writing a similar thing twice. Is there any way that I can write a single function inOrder that can take either pure or monadic functions?

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  • Random forests for short texts

    - by Jasie
    Hi all, I've been reading about Random Forests (1,2) because I think it'd be really cool to be able to classify a set of 1,000 sentences into pre-defined categories. I'm wondering if someone can explain to me the algorithm better, I think the papers are a bit dense. Here's the gist from 1: Overview We assume that the user knows about the construction of single classification trees. Random Forests grows many classification trees. To classify a new object from an input vector, put the input vector down each of the trees in the forest. Each tree gives a classification, and we say the tree "votes" for that class. The forest chooses the classification having the most votes (over all the trees in the forest). Each tree is grown as follows: If the number of cases in the training set is N, sample N cases at random - but with replacement, from the original data. This sample will be the training set for growing the tree. If there are M input variables, a number m « M is specified such that at each node, m variables are selected at random out of the M and the best split on these m is used to split the node. The value of m is held constant during the forest growing. Each tree is grown to the largest extent possible. There is no pruning. So, does this look right? I'd have N = 1,000 training cases (sentences), M = 100 variables (let's say, there are only 100 unique words across all sentences), so the input vector is a bit vector of length 100 corresponding to each word. I randomly sample N = 1000 cases at random (with replacement) to build trees from. I pick some small number of input variables m « M, let's say 10, to build a tree off of. Do I build tree nodes randomly, using all m input variables? How many classification trees do I build? Thanks for the help!

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  • Dynamically assembling SQL queries in Java

    - by kd
    What is the best way to assemble an SQL query with join conditions dynamically? I don't want to hard code the query for each different condition on a webpage or a set of webpages. Is it even feasible? I got as far as being able to assemble simple queries but i got stumped when i needed to insert join conditions, i.e. how to figure out dependencies for joins etc.

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  • B- trees, B+ trees difference

    - by dta
    In a B- tree you can store both keys and data in the internal/leaf nodes. But in a B+ tree you have to store the data in the leaf nodes only. Is there any advantage of doing the above in a B+ tree? Why not use B- trees instead of B+ trees everywhere? As intuitively they seem much faster. I mean why do you need to replicate the key(data) in a B+ tree?

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